The invention relates to a magnesium alloy for technical applications and to the use of such an alloy for producing extruded semi-finished products and components and for producing sheet.
Magnesium alloys are lightweight materials that are used in automotive engineering, engine construction, aerospace engineering, and other lightweight designs.
With very good strength properties and a low specific weight, magnesium alloys are especially suitable as metal construction materials for vehicle and aircraft construction.
Especially in vehicle construction it is necessary to reduce weight because additional elements are built in due to rising standards for comfort and safety. Lightweight construction is also important for the design of energy-saving vehicles. When processing magnesium materials, the methods used—primary shaping by die-casting and shaping by extrusion, forging, rolling, stretch-forming or deep-drawing—become increasingly significant. Lightweight components that are enjoying increasing demand, especially for vehicle construction, can be produced using these methods.
Known from DE 806 0055 is a magnesium alloy that constitutes a composition of 0.5 to 10% metals from the group of rare earths, and the remainder magnesium, with the provision that the rare earths constitute at least 50%, preferably at least 75% neodymium, at most up to 25% lanthanum and cerium separately or together, and praseodym and small quantities of samarium and traces of the elements of the yttrium group as the remainder, one or a plurality of the following elements being added: manganese, aluminum, calcium, thorium, mercury, beryllium, zinc, cadmium, and zirconium.
Known from DE 42 08 504 A1 is a magnesium alloy that contains 2 to 8% rare earth metals, the rare earth metal comprising samarium.
Other alloys that in addition to the main component include magnesium, manganese, and other elements from the group of the rare metals and/or aluminum, copper, iron, nickel, calcium, etc., are known for instance from DE 199 15 276 A1, DE 196 38 764 A1, DE 679 156, DE 697 04 801 T2, DE 44 46 898 A1.
The known magnesium alloys have various disadvantages.
In the presence of calcium, heat cracks can occur after casting in a casting process that has a rapid cooling speed, for instance injection molding. The strength of alloys that include magnesium-aluminum-zinc-manganese or magnesium-aluminum-manganese declines at higher temperatures.
Overall the shaping behavior, weldability, and resistance to corrosion deteriorate.
The cold formability of the most common magnesium alloys is limited due to their hexagonal crystal structure and low ductility. Most magnesium alloys are brittle at room temperature. For certain shaping methods for producing semi-finished products from magnesium alloys, ductility is necessary in addition to high tensile strength. Higher ductility enables improved shaping and forming, and sometimes also higher strength and toughness. Many of the known magnesium alloys have properties that vary widely with the production condition.